The thorough and timely manner in which you handled the problem here on Cascade was much appreciated. Without exception, your people were thoughtful, considerate, and professional. I felt you and your company handled my problem efficiently and carefully, and that we were in good hands.

Sheryl A. Fuller

Overall one of the better EMPs ever submitted to the Departments Solid Waste Section, thank you for putting this together.

Thank you for your assistance through this circus of errors, misinformation, lack of communication, and inefficiency. At times it seemed beyond redemption. Your project manager was magnificent, and we wish to emphasize that he had the only clear mind, the only steady hand, the only source of common sense in the whole battery of bureaus, departments, and businesses

Otis Wilson

Thank you, Steve! You have no idea how much I appreciate the way you have handled this

James R. Templin CSCEO Investors Mortgage Co.

Risk-Based Assessment Requirements

The Oregon Department of Environmental Quality (DEQ) has established guidance for completion of risk-based assessments. This guidance was first presented in the Risk-Based Decision Making for Remediation of Petroleum-Contaminated Sites (RBDM Guidance) dated September 22, 2003. Risk-based concentration (RBCs) or cleanup standards presented in the RBDM Guidance have periodically been updated with the most recent version issued September 15, 2009.

In summary, risk-based assessment requires answering the following questions:

What is risk? Risk = Toxicity x Exposure

To assess risk at a contaminated site, you must have information about the following:

The nature of the release (what kinds of contaminants are there?)

The magnitude of the release (what are the contaminant concentrations?)

The extent of the contamination (soil, groundwater, on-site, off-site?)

The toxicity of the identified contaminants (carcinogens, non-carcinogens?)

What are applicable exposure pathways?

Direct contact with contaminated soil resulting in exposure due to a combination of dermal contact, soil ingestion, vapor inhalation, and particulate inhalation

Leaching from soils to underlying groundwater with subsequent groundwater ingestion

Volatilization from soils to outdoor air and subsequent inhalation

Volatilization from soils to indoor air and subsequent inhalation

Ingestion or other exposure to contaminated groundwater

Volatilization from groundwater to outdoor air and subsequent inhalation

Volatilization from groundwater to indoor air and subsequent inhalation

What are applicable receptor scenarios?

Adults and children in a residential scenario (single family housing)

Adults and children in an urban residential setting (apartment, condominium)

Adults in an occupational scenario

Adults in a construction worker scenario

Adults in an excavation worker scenario

Having determined applicable exposure pathways and receptor scenarios, actual contaminants of concern (COC) can be compared to established RBCs or cleanup standards. Where it can be demonstrated that COC are below RBCs for all applicable exposure pathways and receptor scenarios, no further investigative or cleanup will be required.